We are studying normal and abnormal sexual development in the primate. Specifically, we have examined pulsatile secretion (LH, FSH, LH bioassay and testosterone) in the hypothalamic-pituitary-testicular axis. The primate age range has been from 10 days of age to adult. Our current plans are the expansion of this research to include fetal sexual development. We have also studied the effects of castration, gonadotropin hormone releasing hormone, and human chorionic gonadotropin at various ages. Other studies conducted in the course of this research include fluorescent labeling of testicular tissue, light and electron microscopy of the testis. Our previous research with rat and bovine sertoli cell culture systems has been applied to our current primate investigation and will soon be applied to human tissue. Investigation continues in the following areas: 1) pituitary resistance to thyroid hormone in cystinosis, osteogenesis imperfecta and neonatal hypothyroidism, 2) GnRH antiserum studies, 3) cranial irradiation studies, 4) clinical hGH investigations using hGH prepared by recombinant DNA technology.